EU leaders warned that leaving the 28-member bloc would be final, as two polls indicated the "Leave" camp was just ahead of "Remain". "If you jump out of the airplane, you cannot clamber back through the cockpit hatch," Cameron warned, his sleeves rolled up and pointing for emphasis. "Put your children's future first." As planes with banners from the rival campaigns flew over London to woo the undecided, two polls showed the "Leave" side with the slimmest of leads, both within the margin of error.
"Our latest poll suggests that Leave is in a stronger position than Remain," said Luke Taylor of TNS, after their poll put "Leave" on 43 percent and "Remain" on 41 percent. Record numbers of voters have registered for the ballot, and Taylor emphasised the result could all come down to turnout. A Brexit vote would mean Britain would be the first country to leave the European Union in the bloc's 60-year history, leaving it in uncharted waters at an already troubled time.
"Out is out," European Commission chief Jean-Claude Juncker said in Brussels, dismissing any talk of a post-vote renegotiation just hours before polls open. French President Francois Hollande warned an exit would be "irreversible" while German Chancellor Angela Merkel said she wanted Britain to stay but that the decision was down to the British people.
The German and French leaders will meet in Berlin next week for talks Hollande said would work "towards relaunching the European project", already struggling with an unprecedented migrant crisis. Cameron's main rival in the "Leave" campaign and possible successor, Boris Johnson, said Britain stood on the brink of "independence day" from Europe. "I do think that we are on the verge, possibly, of an extraordinary event in the history of our country and indeed in the whole of Europe," Johnson said in eastern England.
Nigel Farage, leader of the anti-EU UK Independence Party, said: "I genuinely believe we are going to win this." US Republican White House hopeful Donald Trump, who arrives in Britain Thursday, also spoke out on Brexit again, saying he thought the country should "go it alone". A British withdrawal would trigger a lengthy exit negotiation, leading to the loss of unfettered access to its partners in the 28-nation market and forcing the country to strike its own trade accords across the world.